1. Field of the Invention
The invention relates to the art of injection molding hollow plastic articles, especially hollow plastic articles which are to be blow molded into containers and, more particularly, to a method and apparatus for transferring hollow plastic articles from an injection molding station to a blow molding station.
2. Description of the Related Art
Numerous methods are known for the transfer of parisons or preforms from an injection molding station to a blow molding station.
One of the primary concerns in transferring such articles is providing efficient use of both the injection molding machine and the blow molding machine. The injection molding process differs from the blow molding process, particularly in the time needed to complete each process. Thus, one station frequently must wait for the other and, therefore, operates in an inefficient manner.
U.S. Pat. Nos. 4,690,633 to Schad and 4,140,464 to Spurr are examples of prior art methods for preparing articles involving a transfer of the articles from an injection molding station to a blow molding station. In both cases, all the preforms molded in one molding cycle of the injection molding station are unloaded and transferred "en masse" to the next station. Such "en masse" transfer of preforms generally results in either a backlog of preforms at the blow molding station, or inefficient use of the blow molding station due to periods of delay or slow operation while waiting for a new batch of preforms to be delivered from the injection molding station.
Another method for transferring preforms is shown in U.S. Pat. No. Re. 33,237 to Delfer, which deals with a carrier plate cooperating with an injection molding machine.
A method of altering the spacing between the parts removed by a robot's tooling plate is disclosed in U.S. Pat. No. 4,814,134 to Brown.
It is the principal object of the present invention to provide a novel method and apparatus for unloading preforms from a mold to a receiving station for conveyance to a blow molding machine.
It is another object of the present invention to provide such a method and apparatus wherein robot tooling need not necessarily be equipped to change spacing of preforms or articles being transferred, thereby simplifying the robot tooling and reducing its weight and cost.
It is still another object of the present invention to provide such a method and apparatus having great flexibility so as to accommodate many differing configurations of preform injection mold cavity number and layout, blow mold cavity number and layout and a variety of pallet configurations.
Other objects and advantages will become apparent to those skilled in the art upon a consideration of the following disclosure.